It is not known when the ravens first came to the Tower of London, but their presence there is surrounded by myth and legend. Unusually for birds of ill omen, the future of both Country and Kingdom relies upon their continued residence, for according to legend, at least six ravens must remain lest both Tower and Monarchy fall. There are seven ravens at the Tower today (the required six plus one spare). Their names are Jubilee, Harris, Gripp, Rocky, Erin, Poppy, and Merlina. Their lodgings are next to the Wakefield Tower.

Source: Historic UK